1. Field of the Invention
The present invention is directed to a computer tomography apparatus of the type wherein an x-ray source and a radiation detector are rotated on a frame around a patient, and in particular to such a computer tomography apparatus wherein the detector is resiliently mounted on the frame permitting slight displacement of the detector in a direction tangent to the orbit of the detector around the patient.
2. Description of the Prior Art
Computer tomography devices are known in the art wherein an x-ray source and a radiation detector are mounted on a frame which is rotated around a patient. The radiation detector consists of a row of detector elements, and the x-ray source emits a fan-shaped x-ray beam in which the patient is disposed. The frame, with the x-ray source and the radiation detector carried thereon, is rotated around the patient so that the patient is irradiated by the x-ray beam from different directions. The axis of rotation of the frame is perpendicular to the plane containing the x-ray beam. Radiation attenuated by the patient is incident on the x-ray detector, which converts the radiation into electrical signals. The signals are supplied to a computer which constructs a cross-sectional image (slice) of the examination subject from the measured values of the radiation detector.
It is also known to provide such a computer tomography apparatus with means for deflecting the focus of the x-ray source in the fan plane perpendicular to an axis of symmetry of the radiation detector. This results in an increased total number of image values, and thus achieves an improved image resolution in comparison with operation wherein the focus has a fixed position. The rated or known position of the focus is prescribed relative to the rotating frame, because in conventional devices the radiation detector is stationarily mounted on the rotating frame, and is therefore assumed to have fixed and unchanging position relative to the frame. Because of this rigid mounting, however, mechanical forces are transmitted from the frame to the radiation detector, and jolts and other jarring forces acting on the frame will similarly jolt or jar the radiation detector, possibly giving rise to noise signals leading to image artifacts.